The automated systems for awnings generally envisage the use of a gear motor for moving the awning and an associated wind or vibration sensor.
Control of the external stresses acting on the awning, for example due to atmospheric phenomena, is important in order to protect its structure. The greater the surface area of the awning the greater is the force exerted on the mechanical structure, usually a folding arm, supporting it. Basically the awning acts in the manner of a sail. The stresses transmitted from the awning to the structure or to the gear motor may damage them unless the awning is promptly and automatically retracted.
In the known art there are many automatic retraction systems.
U.S. Pat. No. 5,307,856 envisages the installation of a sensor operationally connected to and forming an integral part of the arm of the awning.
DE19904226 describes a controller for detecting vibrations induced on the arm by the wind, which is situated in a corner of the window. Detection of the vibrations is performed by means of a photosensor.
EP1069257 envisages an awning control system equipped with a vibration sensor or accelerometer situated on an extendable arm.
DE19991032729 envisages an anemometer for controlling and operating an awning.
FR2792794 envisages a vibration and impact detector arranged in the structure which is at the free end of the awning support arm.
In other cases, as in U.S. Pat. No. 5,307,856 and EP1069257, the detection device or sensor is included within the mechanical structure of the awning, for example in the extendable arms.
If installed inside the extendable arms, the device/sensor constitutes an unnecessary cost for all those users who do not intend automating the awning. It is not possible to remove the device/sensor. Moreover this type of installation is not devoid of drawbacks since the device or sensor must be adapted to the type of extendable arm and must necessarily be connected to the electrical power line and to the unit which controls the awning motor.
Other accessory devices installed on the outside of the awning structure are, on the other hand, advantageous since the user has the choice of purchasing them or not, but they constitute an additional cost which the user must bear at the time of installation. Powering and connection to the motor control unit of the electrical mains devices is particularly difficult and costly. If powered by batteries and provided with a wireless connection to the motor, the device or sensor must be able to be easily controlled constantly by the user in order to prevent interruption of operation without warning, an event which could have disastrous consequences for the awning. In some cases checking the battery of the device and replacing it may be dangerous, as for example in the case of sun awnings which are situated on the outside of a multi-storey building.
Often awning retailers sell their products in combination with a particular motor/operating system made by a certain company such that the motor/operating system is provided ad hoc or to suit a specific need. Therefore the manufacturers of automated systems must provide specially designed wind, vibration or impact sensor devices for each awning or a universal device which may be used for all awnings. The costs of providing and managing this type of service may be considerable.